1. Field of the Invention
The present invention relates to radioactive waste management systems, and in particular to a process employing freezing an electrodialysis for concentration of liquid waste streams.
2. The Prior Art
The U.S. Pat. No. 3,271,163 to Malick discloses a combination process for the removal of radioactive material (strontium 90) from milk employing fractional crystallization and ion exchange media but does not disclose the use of ion exchange membranes or electrodialysis.
The U.S. Pat. No. 3,305,320 to Weech discloses a method of purifying aluminum nitrate employing an alternate melting and crystallization process. It also mentions the invention's applicability to eutectic systems, solid-solution systems and the separation of fission products such as impurities from atomic reactor wastes. The Van de Voorde patent discloses as prior art a chemical coprecipitation method of treating radioactive materials additionally employing filtration of the precipitate dehydrated by "the freeze-thaw method".
The U.S. Pat. No. 3,405,050 to Bovard, et al. discloses the use of electrodialysis and precipitation as prior art in the decontamination of radioactive wastes. The Bovard, et al. invention itself is directed toward radioactive decontamination of wastes by way of a filter employing ion exchange materials and electrolysis. A further reference may be found in the McGraw-Hill Encyclopedia of Science and Technology (5th ed. 1982) which briefly discusses the role of ion exchange resin membranes in dialysis and the utilization of micro- and semimicroelectrodialyzers in radioisotope tracer studies. The Shiroki patent, U.S. Pat. No. 4,483,754 discloses and claims a process of electrolysis of NaCl employing ion exchange membranes but does not, however, mention its use in radioactive waste treatment.
The Carlin, et al. and Van de Voorde patents, U.S. Pat. Nos. 3,922,231 and 3,716,490, respectively, disclose methods for decontaminating radioactive liquids by adsorption of the radioactive materials onto ion exchange material but make no specific mention of ion exchange membranes or dialysis. The L. F. Ryan patent, U.S. Pat. No. 3,520,805, achieves a reduction in volume of liquid radioactive waste by filtration through a finely divided ion exchange resin.